Perhaps I'm misunderstanding something but how can a standard be turned on and off? Can't you just not implement it? Or do you mean Google Search shouldn't show AMP pages?
It's great when I'm on the light rail going through areas with patchy cell signal, but when an article's share buttons are broken because it's the AMP version it's a pain to figure out how to navigate to the non-AMP version of the article.
A couple news sources (usually technical ones) thankfully put a link to the non-AMP version somewhere on the page, but IMHO this should be automatically done for every AMP link opened.
That is available in the standard markup, so it should maybe just be added to the UI (in the ellipsis menu probably).